Much of modern personal communication, both in social and business environments, takes place through the telephone. Yet, there are many persons in society who have attenuated hearing capability and are thus disabled or incapable or handicapped in using the voice telephone system commonly in use today. For person who are deaf, there has for some time been a system of communication through the telephone system which has been used by the deaf community. That system makes use of devices known as telecommunication devices for the deaf (TDDs), also known as text telephones (TTYs). Current TDDs are electronic devices consisting of a keyboard and a display and a modem, to acoustically or directly couple to a telephone line, which permit the user to type characters into their keyboard, with the characters then be encoded and transmitted over the telephone line to be displayed on the display of a communicating or remote TDD.
Current TDD communication is conducted in a code, known as Baudot or Baudot/Weitbrecht, which evolved historically at a time when many telecommunication devices for the deaf were based on mechanical or electromechanical devices rather than the current generation of electronic devices. Accordingly, the Baudot protocol was constructed for a set of constraints which are no longer relevant to present day devices. The original Baudot protocol was a uni-directional, or simplex, system of communication conducted at 45.5 baud. The normal Baudot character set consists of a 5 bit characters, and the system is a bitonal system based on 1400 and 1800 hertz tones. The protocol does not utilize a carrier when no signals are being sent, and because of the protocol for character transmission, which includes a start bit and at least 11/2 stop bits, it is only possible to send approximately 6 characters per second, one way, during conventional Baudot communications.
In spite of its limitations, the Baudot communication system, and TDDS, are widely used within the community of persons who are deaf. In addition, systems have been implemented to permit users of the TDD system to communication with hearing people. This is done through the use of a so-called "relay." A relay, as used herein, refers to a system of voice to TDD communication which uses an operator referred to as a call assistant who serves as an intermediate between a hearing user on one telephone line and a deaf TDD user on a second telephone line. The call assistant wears a headset to communicate by voice with the hearing user and also has access to a TDD so that the call assistant can communicate with the deaf user via the TDD. Thus, the call assistant serves as an intermediary between the deaf person and the hearing person so as to, in effect, translate from voice to digital electronic forms of communication.
While the TDD communication system has a constituency within the deaf community, it is not widely used by persons who are deficient in hearing capability, but would not describe themselves as deaf. Many otherwise fully able persons, particularly elderly ones, suffer attenuated hearing capability due to aging, disease, or other traumatic condition. Many persons who have some degree of hearing capability left do not consider themselves "deaf," and therefore will tend not to avail themselves of specialized equipment intended for the deaf community. If a person has spent much of his or her life engaged in oral communication using the spoken word in the telephone, it is difficult to accept that telephonic communication may become difficult or impractical as one's hearing declines in efficiency. No system has heretofore existed which is capable of assisting the person who has significant hearing loss, in communication over the telephone in a manner which emulates, to the fullest extent possible, the normal telephonic communication patterns of hearing people.